Do you ever wonder if we are alone in the Universe? If yes let's go to explore our Solar System looking for signs of Life.
Let us begin from our neighbors.
How to start our research? A first hint can come from analyzing the zone around the Sun where gravity and temperature is suitable for keeping liquid water.That zone around a Star is called Goldilock or Habitable zone.
|solar system habitable zone|
Life on Mars?
Mars probably is the most studied Planet in Solar System. Many missions including Mariners 4,6,7 and 9, the Viking orbiters and landers 1 and 2, Mars Pathfinder, Mars Global Surveyor, Mars Odyssey, Mars Express, Spirit, Opportunity, Mars Reconnaissance Orbiter, and Phoenix have orbited and actually landed on the surface of Mars to study the Planet and in search of life.
Now pictures of Mars soil are so frequent and high resolution that everybody have a clear understanding of what we could find on Mars.
|Mars 4.5 billions years ago|
But what about life? What has changed from when in 1877, the italian astronomer Giovanni Schiaparelli observed Mars through his telescope and observed what he thought were handmade canals? What we know now is that in the past oceans covered the Mars surface. The Scientists have developed a picture of what it would have appeared Mars in the past.
That is impressive since similarly to Earth, on Mars Life could have been developed in the oceans covering his surface.
The other Solar System's Planet are outside of the Habitable Zone but local conditions could have been suitable to develop life. Especially some Jupiter Moon can reserve some surprises.
Resources: The Planet Mars (all you want to know about Mars missions and Data)
Europa. Galileian Jupiter's Moon
Probably Europa is the most likely celestial body we know suitable to support developing life. Why? Its surface seems to be a thick layer of ice. Because of the way Europa’s magnetic field seems to behave, astronomers suspect that beneath the ice on Europa there is a global ocean of saltwater.
The water probably remains liquid because of tidal heating from Europa’s interaction with Jupiter and the other large moons. It is not clear how thick the ice is or how deep the ocean is. The ice and water combined are probably a shell between 70 and 170 km thick on top of a rocky surface. The ice is most likely at least 3-4 km thick, and may be as thick as 25 km.
This environment might be similar to some of the underground lakes in Antarctica that are being explored and likely contain life. Some mission are planned to go on Europa to look for life inside the icy crust.
What have we to expect from Europa liquid inner oceans? Marine monsters? We will see it.
Resources insights: Unmasking Europa: The Search for Life on Jupiter's Ocean Moon
Ganymede. Jupiter's Moon
Ganymede, another Jupiter Moon has some environments suitable for life. Ganymede is the largest moon in the solar system also seems to have a saltwater ocean beneath an ice crust. The energy from the tidal interactions between Ganymede and the other Galilean moons should not generate enough energy to keep saltwater liquid on this moon, and astronomers think the water is probably kept liquid by a liquid iron core inside the moon, and the insulation of a the ice which is hundreds of kilometers thick. Ganymede also seems to have a very thin atmosphere.
Recently a team at NASA by means of Hubble telescope picture has been capable to demonstrate the existence of the salt oceans underneath the Ganymede crust.
By watching the rocking motion of the two aurorae, scientists were able to determine that a large amount of saltwater exists beneath Ganymede’s crust affecting its magnetic field.
The situation is similar to that of Europa. A salt liquid ocean is perhaps suitable to develop life and in billion of years it could be likely.
Callisto. Jupiter's Moon
|callisto inner structure|
For years Callisto has been thought a dead Moon but the presence of liquid salt water between ammonia could furnish the base elements for developing life even if the life conditions would be very extreme in those places.
On Earth have been discovered a third class of microorganisms. These microbes called archaeabacteria, or simply "archaea", constitute a third branch of life on Earth, along with prokaryotes (normal bacteria) and eukaryotes (plants and animals). Like prokaryotes, the genetic material of archaeabacteria float freely throughout the cell -- they are not contained within the cell nucleus like eukaryotic organisms. However, the DNA of archaeabacteria more closely resemble that of plants and animals than normal bacteria. They are truly in a class by themselves, and if life is discovered elsewhere in the solar system it may be similar to the archaeabacteria of Earth.
Titan. Saturn's Moon
|Titan - in black liquid methan lakes|
Well Titan! It is the only moon in the solar system that has a significant atmosphere. The atmosphere is about 1.5 times the atmospheric pressure on Earth and is composed mainly of nitrogen and a small amount of methane. Titan’s surface is very cold, about -180°C, and is covered in lakes or perhaps even oceans of liquid methane. Methane may exist as a solid liquid and gas on Titan, and may behave much like water does on Earth, regulating climate and causing weather. Lightning has not been detected in the atmosphere, but over the course of billions of years, amino acids and other complex molecules might have had time to develop.
Particularly interesting is an experiment conducted recently by graduate student James Stevenson, astronomer Jonathan Lunine and chemical engineer Paulette Clancy.
How could life have been developed on Titan without waterTitan, the giant and cold moon of Saturn, hosts methane-ethane seas and an atmosphere that follow a cycle as on Earth but based not on the water cycle but on methane. Titan is a planetary body awash with seas not of water, but of liquid methane, it could harbor methane-based, oxygen-free cells that metabolize, reproduce and do everything as life on Earth does.
James Stevenson, Jonathan Lunine and Paulette Clancy theorized cell membrane, composed of small organic nitrogen compounds and capable of functioning in liquid methane temperatures of 292 degrees below zero. Their research is published in Science Advances, Feb. 27 - 2015.
On Earth, life is based on the phospholipid bilayer membrane, the strong, permeable, water-based vehicle that houses the organic matter of every cell. A vehicle made from such a membrane is called a liposome. But what if cells weren’t based on water, but on methane, which has a much lower freezing point? The engineers named their theorized cell membrane an “azotosome,” “azote” being the French word for nitrogen. “Liposome” comes from the Greek “lipos” and “soma” to mean “lipid body;” by analogy, “azotosome” means “nitrogen body.”
Titan could be the ideal place to develop life based on Azotosome!
Titan has been already subjected to exploration and also to a landing mission. Huygens was the atmospheric entry probe that landed successfully on Saturn's moon Titan in 2005. Built and operated by the European Space Agency (ESA), it was part of the Cassini–Huygens mission and became the first spacecraft ever to land on Titan.
The probe was also equipped by a microphone that returned a sound. That is one of the firsts sound to be recorded in an alien environment.
You can hear it here: sound from Titan.
Even if Huygens images do not reveal any Titan Azotosome inhabitant walking around it is believed that some living form could really exist in methane lakes.
Due to the very interesting Saturn Titan and Enceladus system it has been planned a new mission to be launched on 2020. Here are the details.
Resources: if you want to read more about Titan and achieve more detailed data you should read the book: Titan Unveiled: Saturn's Mysterious Moon Explored. I did it and enjoyed a lot! Have good read.
Enceladus, Saturn Moon
It is white and reflects almost 100% of the light that strikes it. It also has geysers on its surface that shoot out jets of water with ammonia and organic compounds.
The temperatures near these geysers are likely very high, while the rest of the moon is very cold with an average temperature of about 220 °C.
The Saturn moon Enceladus harbors a big ocean of liquid water beneath its icy crust that may be capable of supporting life as we know it.
The water ocean on Enceladus is about 6 miles (10 kilometers) deep and lies beneath a shell of ice 19 to 25 miles (30 to 40 km) thick, researchers said. Further, it's in direct contact with a rocky seafloor, theoretically making possible all kinds of complex chemical reactions such as, perhaps, the kind that led to the rise of life on Earth.
If you arrived at the conclusion of this post it means you are really interested in life beyond Earth. Moreover We talked about the Solar Systems possibilities and we found 6 places where life could have developed in the past or could develop in the future.
That is incredible how much things we could learn about our home the Solar System and soon we could have a proof that we are not alone even in our environment.
What do you think about? I'd like to hear from you.